Apr 262019

Code name : ’86S100′.Nothing really ‘TOP SECRET ‘, just a little custom IC you can find on many Capcom arcade PCBs from pre-CPS1 era.To name few :

  • 1943
  • Bionic Commando
  • Black Tiger/Black Dragon
  • Mad Gear
  • Rush & Crash/The Speed Rumbler
  • Side Arms
  • Street Fighter

The chip is a 28 pin one with plastic package and pitch of 1.778mm :

Sometimes you can find it under different part name but same functions, like on a Mad Gear PCB :

This custom IC is involved in graphics generation being directly connected to data bus of the GFX ROMs as shown on Bionic Commando schematics:

Being a not really reliable part (sometimes you can find it literally ‘fried’) and quite hard to obtain as spare I decided to give a try to reproduce it.As usual I looked at how bootlegers re-engineered it and how the custom functions were implemented in earlier Capcom hardware.I succeeded in my purpose it but I actually had to make two versions of it because the original ’86S100′ can work in two modes depending on the logical state of its pin 1 (if hard-wired to GND or VCC).

Here’s final testing of both reproductions on a Bionic Commando and 1943 PCBs:


 Posted by at 7:29 pm

  7 Responses to “Capcom ’86S100′ reproduction”

  1. great work once again caius.
    I recently used one of your custom for a kung fu master board. worked great!

  2. Nice work as always my friend.

    What kind of symptoms does a broken 86S100 give, are the sprites, in this case, missing all together or are there graphic glitches?

    • It depends from how much the custom is damaged internally.Usually you have sprites or backgrounds glitches (the 86S100 is used for both).If the custom is totally dead you will get no sprites or backgrounds but only some squares sign that the custom is not outputting any data.

      • Can wrong colors be a symptom?

        • Yes, the lack of data from a faulty ’86S100′ can make the affected graphics appear like they had wrong colors.

  3. “Nothing really ‘TOP SECRET ” but it should work with “top Secret” 🙂

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